Means for adjusting anodes in electrolytic cells having horizontal cathodes



Get. 17, 1967 w. HONSBERG ETAL MEANS FOR ADJUSTING ANODES INELECTROLYTIC CELLS HAVING HORIZONTAL CATHODES Filed April 21, 1964 2SheetsSheet 1 FIG. 2

INVENTORS:

WERNER HON'SBERG HEINRiCH MUELLER ATT'YS Oct. 17, 19 67 w. HONSBERG ETAL3,347,769

MEANS FO DJUSTING ANODES IN ELECTROLYTIC CEL HAVING HORIZONTAL CATHODESFiled April 21, 1964 2 Sheets-Sheet 2 INVENTORS:

WERNER HONSBERG HEINRlCH MUELLER United States Patent 3,347,769 MEANSFOR ADJUSTING ANODES IN ELEC- TROLYTIC CELLS HAVING HORIZONTAL ABSTRACTOF THE DISCLGSURE Adjustable mounting means for the anode plate in anelectrolytic cell having a horizontal cathode with the anode plateattached to a vertical shaft extending through an opening in the coverof the cell, the adjustable mounting means including a supporting memberresting loosely On the cell cover and carrying a rotatable nut which isthreaded on the upper end of the anode shaft to lower or lower or raisethe anode plate, and an elastomeric plug inserted in the opening of thecell cover around the shaft to hold the shaft in a vertical position andto seal off the opening, this plug having grooves extending outwardlyfrom its inner circumferential surface which contacts the shaft. Thecombination of apparatus is useful in the construction of alkali metalchloride electrolytic cells.

This invention relates to an alkali metal chloride electrolytic cellhaving horizontal cathodes and relates particularly to means foradjusting the anodes in such an electrolytic cell.

The graphite anodes in alkali metal chloride electrolytic cells undergoelectrochemical and mechanical wear in use. Consequently the anodes,which are usually in the form of plates, become gradually thinner untileventually their replacement by fresh anodes becomes inevitable. Thedistance between the anode and cathode increases continually owing tothe wear, so that the internal resistance of the cells increases and thecell voltage rises. Rise in the cell voltage is counteracted byperiodically moving the anode towards the cathode. Inelectrolytic cellshaving horizontal cathodes, particularly mercury cathodes, the anode islowlered toward the cathode.

Graphite anodes of electrolytic cells of this type usually consist ofplates and a shaft which serves to secure the anode to the cell coverand also to supply current to the anode. The shaft is either screwedinto-the anode plate or connected by a tapered surface, and both partsmay be pegged by means of hard rubber pegs to make the connectionsecure.

A number of means has become known for securing and adjusting suchanodes. These means must be such that the anodes can be moved verticallywithout rotation and an adequate seal between the anode shaft and thecell cover is ensured at the point where the shaft passes through thecover. These conditions can only be achieved by compromises in the priorart means.

The simplest mounting known consists of a bored rubber bung, the anodeshaft being passed through the hole in the bung. The rubber bung ispushed into the opening in the cell cover with such force that not onlyis a guide provided for the anode shaft, but the anode is held securelyin position owing to the high friction between the shaft and the bung.Guiding of the anode is unsatisfactory in the said arrangement. Moreovermovement of the anode can only be effected downwardly and a considerablepressure must be exerted on the shaft to achieve such movement.

3,347,769 Patented Oct. 17, 1967 Another prior art adjusting meansconsists of a supporting frame rigidly mounted on the cell cover overthe anode opening and provided with a movable guide nut. The guide nutengages in a threaded steel sleeve applied to the upper portion of theanode shaft, by means of which it is possible to adjust the height ofthe anode. To prevent rotation of the shaft during adjustment, a specialguide for the shaft is necessary. A gastight seal of the shaft withrespect to the cell cover is achieved by a system consisting of astuffing box rigidly secured to the cell cover and having a rubber ringand gland. While this system ensures a satisfactory guiding andadjustment of the anode shaft, it requires great expenditure formaterial and by reason of its relatively complicated construction itsmounting is timeconsuming and in part diflicult when it is necessary tochange an anode.

An adjusting means is also known in which the upper part of the anodeshaft, which is provided With a screwthread, is passed through a nutwhich bears on a supporting member rigidly arranged on the cell cover. Aseal is effected by means of a diaphragm of soft rubber which is securedto a i'ubberized support provided on the cell cover. It is also verydifilcult to change anodes with this arrangement. The sealing membranehas only a short life because of the large surface which it offers toattack by chlorine. It is an object of the present invention to providemeans for adjusting anodes in electrolytic cells having horizontalcathodes which are simple in design, which allow easy movement of theanode and which ensure satisfactory guiding of the anode during themovement.

In the adjusting means according to the present invention, in which theanode shaft is provide at its upper end with a screwthread which engageswith the screwthread of a nut carried by supporting means resting on thecell cover, these objects are achieved in that the nut is carried by, orformed in one with, a rotatable supporting member resting loosely on thecell cover and the anode shaft, at the level at which it passes throughthe cell cover, is sealed by means of a plug of elastomeric materialhaving a central opening provided with grooves or a labyrinth.

The plug of elastomeric material having a grooved or labyrinth opening,for example of natural rubber or silicone rubber, used for the seal isadvantageously cylindrical. To ensure a particularly firm seating of theplug in the opening in the cell cover, the latter is extended upwardlyto form a support. With an opening having this shape, the plug isadvantageously shaped so that its upper portion is extended to form acollar which is turned over the upper end of said support.

To reduce friction between the plug and the anode shaft, the outersurface of the anode shaft and the inner surface of the plug which isprovided with parallel grooves or with interengaging helical grooves maybe greased with a suitable grease. To achieve a satisfactory seal, theinner surface of the plug is provided with about four grooves. It is ofcourse also possible to decrease the number of grooves to one or toincrease the number.

The anode shaft and the thread superposed thereon or provided thereinmay be made of graphite or metal. It is advantageous to choose a metalnut when the thread is made of graphite, and vice versa.

The adjusting means according to this invention offers a number ofadvantages over the conventional adjusting means having comparableadjustment accuracy. Breakage of the anode plates during assembly of thecells is avoided by the loose mounting of the adjusting nut on the cellcover in association with the sprung guiding of the anode shaft in thegrooved plug. The anode is positively located in horizontal position. Inthe case of sudden pressure impulses, which sometimes occur in the gasspace of the cell, if a chlorine detonating gas explosion should occurat a point in the gas system, the anode at the point in question ismerely lifted slightly and the shaft thereof is forced through thegrooved plug. Contrasted with anodes which are connected rigidly withthe cell cover, breakage of expensive anode plates is precluded,prolonged interruption of operation to exchange anodes thereby beingalso avoided. Since the adjusting means according to this inventionconsists of only a few inexpensive and simple elements, only very shortinterruption of operation is necessary to change anodes. Owing to thesimple construction of the adjusting means, change of anodes can becarried out by unskilled labour. Another considerable advantage is thatthe anodes are maintenance free throughout their lifetime. The easyrunning of the adjusting nut on the thread makes it unnecessary toprovide a separate guide for the anode shaft in vertical direction inorder to prevent rotation of the shaft.

FIGURES l to 4 of the accompanying drawings show embodiments ofadjusting means according to this invention.

In FIGURE 1, the anode plate 2 is rigidly connected with the anodeshaft 1. The upper portion of the shaft is provided with a screwthread 3which engages in a not 5 formed in one with a support member 4. Thesupport member rests loosely on the cover 6 of the cell. The opening inthe cell cover for the anode shaft has an upward flange 7 in which isplaced a plug 8 having a grooved opening and which tapers downwardly.The

graphite anode may be raised or lowered by rotating the support memberdirectly by hand or indirectly by means of a suitable key. When loweringthe anode it is not necessary to exert pressure on the anode shaft, butrather this happens merely by the weight of the anode itself.

FIGURE 2 illustrates an adjusting means in which the nut 21 is separatefrom the support member 22, the latter being stationary and the nutbeing adapted to rotate on it. The anode shaft 23 and the anode (notshown) carried by it may be raised or lowered by rotation of the nut.Rotation of the nut may be carried out with a special key or manually.In the latter case, the nut may advantageously be provided with a handle24.

In order to save graphite, the threaded portion of the anode shaft maybe made of metal and fixed to the anode shaft in a conventional way. Inthis case the nut may be made of graphite to prevent seizing.

FIGURE 3 is a sectional elevation of a grooved plug 31 having fivegrooves 32 and a superposed collar 33.

In FIGURE 4, the anode shaft 41 is passed through a nut 42 made in onewith the support member 43. To minimize friction, the support memberwhich is not rigidly connected with the cell cover 44 rests'on a slidering 45 which lies loosely on the cover. The slide ring may be made frommetal or, if electrical insulation between electrode and electrolyzer isdesirable or necessary, from plastics. The collar 47 of plug 48 isturned over the flange 46 provided on the cell cover. The outer surfaceof the plug is greased to improve the seal between the outer surface ofthe plug and the inner surface of the flange. The inner surface of theplug is also advantageously greased.

We claim:

1. In an electrolytic cell having a substantially horizontal cathode, acover enclosing said cell, an anode plate arranged within said cell on avertical shaft extending through an opening in said cover and means foradjustably mounting said anode plate, the improvement wherein said meansfor mounting said anode plate comprises a support member resting looselyon said cell cover and carrying a rotatable nut threadably engaging theupper portion of said shaft for axial adjustment thereof, and anelastomeric plug inserted in the opening of said cell cover around saidshaft to maintain said shaft in its vertical position, said plug beinggrooved radially outwardly on its inner surface which is in sealingcontact with said shaft.

2. Improved mounting means in an electrolytic cell as claimed in claim 1wherein the inner surface of said eiastomeric plug contains a pluralityof superposed annular grooves.

3. Improved mounting means in an electrolytic cell as claimed in claim 1wherein said nut is integral with said support member which restsrotatably on said cell cover.

4. Improved mounting means in an electrolytic cell as claimed in claim 1wherein said plug is cylindrical and is seated firmly in a circularopening of the cell cover concentric with said vertical shaft.

5. Improved mounting means in an electrolytic cell as claimed in claim 1wherein said opening in said cell cover is formed by an upwardlyextending flange of said cover adapted to receive an elongated plug insealing contact with said flange.

6. Improved mounting means in an electrolytic cell as claimed in claim 5wherein the upper portion of said elongated plug is extended to form acollar, said collar being turned down over the upper end of said flange.

7. Improved mounting means in an electrolytic cell as claimed in claim 1wherein said nut is rotatably seated on an upper surface of said supportmember and is maintained at a fixed distance by said support member fromsaid cell cover.

8. Improved mounting means in an electrolytic cell as claimed in claim 7wherein said nut bears handle means for manually turning said nut.

References Cited UNITED STATES PATENTS 379,464 3/1888 Hopkins et al.74-4248 2,643,147 6/1953 Funlchouser et al. I 277-208 2,793,889 5/1957Potter 277-208 3,037,928 6/1962 Hass et al. 204-286 3,080,310 3/ 1963Lindenmaier et al. 204-225 3,256,172 6/1966 Dorfel et al. 204228 JOHN H.MACK, Primary Examiner. R ERT K, MIHALEK, Examiner.

1. IN AN ELECTOLYTIC CELL HAVING A SUBSTANTIALLY HORIZONTAL CATHODE, ACOVER ENCLOSING SAID CELL, AN ANODE PLATE ARRANGED WITHIN SAID CELL ON AVERTICAL SHAFT EXTENDING THROUGH AN OPENING IN SAID COVER AND MEANS FORADJUSTABLY MOUNTING SAID ANODE PLATE, THE IMPROVEMENT WHEREIN SAID MEANSFOR MOUNTING SAID ANODE PLATE COMPRISES A SUPPORT MEMBER RESTING LOOSELYON SAID CELL COVER AND CARRYING A ROTATABLE NUT THREADABLY ENGAGING THEUPPER PORTION OF SAID SHAFT FOR AXIAL ADJUSTMENT THEREOF, AND ANELASTOMER PLUG INSERTED IN THE OPENING OF SAID CELL COVER AROUND SAIDSHAFT TO MAINTAIN SAID SHAFT IN ITS VERTICAL POSITION, SAID PLUG BEINGGROOVED RADIALLY OUTWARDLY ON ITS INNER SURFACE WHICH IS IN SEALINGCONTACT WITH SAID SHAFT.